Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20200117-1' into...
[qemu.git] / block / qed.h
1 /*
2 * QEMU Enhanced Disk Format
3 *
4 * Copyright IBM, Corp. 2010
5 *
6 * Authors:
7 * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
8 * Anthony Liguori <aliguori@us.ibm.com>
9 *
10 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
11 * See the COPYING.LIB file in the top-level directory.
12 *
13 */
14
15 #ifndef BLOCK_QED_H
16 #define BLOCK_QED_H
17
18 #include "block/block_int.h"
19 #include "qemu/cutils.h"
20
21 /* The layout of a QED file is as follows:
22 *
23 * +--------+----------+----------+----------+-----+
24 * | header | L1 table | cluster0 | cluster1 | ... |
25 * +--------+----------+----------+----------+-----+
26 *
27 * There is a 2-level pagetable for cluster allocation:
28 *
29 * +----------+
30 * | L1 table |
31 * +----------+
32 * ,------' | '------.
33 * +----------+ | +----------+
34 * | L2 table | ... | L2 table |
35 * +----------+ +----------+
36 * ,------' | '------.
37 * +----------+ | +----------+
38 * | Data | ... | Data |
39 * +----------+ +----------+
40 *
41 * The L1 table is fixed size and always present. L2 tables are allocated on
42 * demand. The L1 table size determines the maximum possible image size; it
43 * can be influenced using the cluster_size and table_size values.
44 *
45 * All fields are little-endian on disk.
46 */
47 #define QED_DEFAULT_CLUSTER_SIZE 65536
48 enum {
49 QED_MAGIC = 'Q' | 'E' << 8 | 'D' << 16 | '\0' << 24,
50
51 /* The image supports a backing file */
52 QED_F_BACKING_FILE = 0x01,
53
54 /* The image needs a consistency check before use */
55 QED_F_NEED_CHECK = 0x02,
56
57 /* The backing file format must not be probed, treat as raw image */
58 QED_F_BACKING_FORMAT_NO_PROBE = 0x04,
59
60 /* Feature bits must be used when the on-disk format changes */
61 QED_FEATURE_MASK = QED_F_BACKING_FILE | /* supported feature bits */
62 QED_F_NEED_CHECK |
63 QED_F_BACKING_FORMAT_NO_PROBE,
64 QED_COMPAT_FEATURE_MASK = 0, /* supported compat feature bits */
65 QED_AUTOCLEAR_FEATURE_MASK = 0, /* supported autoclear feature bits */
66
67 /* Data is stored in groups of sectors called clusters. Cluster size must
68 * be large to avoid keeping too much metadata. I/O requests that have
69 * sub-cluster size will require read-modify-write.
70 */
71 QED_MIN_CLUSTER_SIZE = 4 * 1024, /* in bytes */
72 QED_MAX_CLUSTER_SIZE = 64 * 1024 * 1024,
73
74 /* Allocated clusters are tracked using a 2-level pagetable. Table size is
75 * a multiple of clusters so large maximum image sizes can be supported
76 * without jacking up the cluster size too much.
77 */
78 QED_MIN_TABLE_SIZE = 1, /* in clusters */
79 QED_MAX_TABLE_SIZE = 16,
80 QED_DEFAULT_TABLE_SIZE = 4,
81
82 /* Delay to flush and clean image after last allocating write completes */
83 QED_NEED_CHECK_TIMEOUT = 5, /* in seconds */
84 };
85
86 typedef struct {
87 uint32_t magic; /* QED\0 */
88
89 uint32_t cluster_size; /* in bytes */
90 uint32_t table_size; /* for L1 and L2 tables, in clusters */
91 uint32_t header_size; /* in clusters */
92
93 uint64_t features; /* format feature bits */
94 uint64_t compat_features; /* compatible feature bits */
95 uint64_t autoclear_features; /* self-resetting feature bits */
96
97 uint64_t l1_table_offset; /* in bytes */
98 uint64_t image_size; /* total logical image size, in bytes */
99
100 /* if (features & QED_F_BACKING_FILE) */
101 uint32_t backing_filename_offset; /* in bytes from start of header */
102 uint32_t backing_filename_size; /* in bytes */
103 } QEMU_PACKED QEDHeader;
104
105 typedef struct {
106 uint64_t offsets[0]; /* in bytes */
107 } QEDTable;
108
109 /* The L2 cache is a simple write-through cache for L2 structures */
110 typedef struct CachedL2Table {
111 QEDTable *table;
112 uint64_t offset; /* offset=0 indicates an invalidate entry */
113 QTAILQ_ENTRY(CachedL2Table) node;
114 int ref;
115 } CachedL2Table;
116
117 typedef struct {
118 QTAILQ_HEAD(, CachedL2Table) entries;
119 unsigned int n_entries;
120 } L2TableCache;
121
122 typedef struct QEDRequest {
123 CachedL2Table *l2_table;
124 } QEDRequest;
125
126 enum {
127 QED_AIOCB_WRITE = 0x0001, /* read or write? */
128 QED_AIOCB_ZERO = 0x0002, /* zero write, used with QED_AIOCB_WRITE */
129 };
130
131 typedef struct QEDAIOCB {
132 BlockDriverState *bs;
133 QSIMPLEQ_ENTRY(QEDAIOCB) next; /* next request */
134 int flags; /* QED_AIOCB_* bits ORed together */
135 uint64_t end_pos; /* request end on block device, in bytes */
136
137 /* User scatter-gather list */
138 QEMUIOVector *qiov;
139 size_t qiov_offset; /* byte count already processed */
140
141 /* Current cluster scatter-gather list */
142 QEMUIOVector cur_qiov;
143 QEMUIOVector *backing_qiov;
144 uint64_t cur_pos; /* position on block device, in bytes */
145 uint64_t cur_cluster; /* cluster offset in image file */
146 unsigned int cur_nclusters; /* number of clusters being accessed */
147 int find_cluster_ret; /* used for L1/L2 update */
148
149 QEDRequest request;
150 } QEDAIOCB;
151
152 typedef struct {
153 BlockDriverState *bs; /* device */
154
155 /* Written only by an allocating write or the timer handler (the latter
156 * while allocating reqs are plugged).
157 */
158 QEDHeader header; /* always cpu-endian */
159
160 /* Protected by table_lock. */
161 CoMutex table_lock;
162 QEDTable *l1_table;
163 L2TableCache l2_cache; /* l2 table cache */
164 uint32_t table_nelems;
165 uint32_t l1_shift;
166 uint32_t l2_shift;
167 uint32_t l2_mask;
168 uint64_t file_size; /* length of image file, in bytes */
169
170 /* Allocating write request queue */
171 QEDAIOCB *allocating_acb;
172 CoQueue allocating_write_reqs;
173 bool allocating_write_reqs_plugged;
174
175 /* Periodic flush and clear need check flag */
176 QEMUTimer *need_check_timer;
177 } BDRVQEDState;
178
179 enum {
180 QED_CLUSTER_FOUND, /* cluster found */
181 QED_CLUSTER_ZERO, /* zero cluster found */
182 QED_CLUSTER_L2, /* cluster missing in L2 */
183 QED_CLUSTER_L1, /* cluster missing in L1 */
184 };
185
186 /**
187 * Header functions
188 */
189 int qed_write_header_sync(BDRVQEDState *s);
190
191 /**
192 * L2 cache functions
193 */
194 void qed_init_l2_cache(L2TableCache *l2_cache);
195 void qed_free_l2_cache(L2TableCache *l2_cache);
196 CachedL2Table *qed_alloc_l2_cache_entry(L2TableCache *l2_cache);
197 void qed_unref_l2_cache_entry(CachedL2Table *entry);
198 CachedL2Table *qed_find_l2_cache_entry(L2TableCache *l2_cache, uint64_t offset);
199 void qed_commit_l2_cache_entry(L2TableCache *l2_cache, CachedL2Table *l2_table);
200
201 /**
202 * Table I/O functions
203 */
204 int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s);
205 int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
206 unsigned int n);
207 int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
208 unsigned int n);
209 int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
210 uint64_t offset);
211 int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
212 uint64_t offset);
213 int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
214 unsigned int index, unsigned int n,
215 bool flush);
216 int coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
217 unsigned int index, unsigned int n,
218 bool flush);
219
220 /**
221 * Cluster functions
222 */
223 int coroutine_fn qed_find_cluster(BDRVQEDState *s, QEDRequest *request,
224 uint64_t pos, size_t *len,
225 uint64_t *img_offset);
226
227 /**
228 * Consistency check
229 */
230 int coroutine_fn qed_check(BDRVQEDState *s, BdrvCheckResult *result, bool fix);
231
232 QEDTable *qed_alloc_table(BDRVQEDState *s);
233
234 /**
235 * Round down to the start of a cluster
236 */
237 static inline uint64_t qed_start_of_cluster(BDRVQEDState *s, uint64_t offset)
238 {
239 return offset & ~(uint64_t)(s->header.cluster_size - 1);
240 }
241
242 static inline uint64_t qed_offset_into_cluster(BDRVQEDState *s, uint64_t offset)
243 {
244 return offset & (s->header.cluster_size - 1);
245 }
246
247 static inline uint64_t qed_bytes_to_clusters(BDRVQEDState *s, uint64_t bytes)
248 {
249 return qed_start_of_cluster(s, bytes + (s->header.cluster_size - 1)) /
250 (s->header.cluster_size - 1);
251 }
252
253 static inline unsigned int qed_l1_index(BDRVQEDState *s, uint64_t pos)
254 {
255 return pos >> s->l1_shift;
256 }
257
258 static inline unsigned int qed_l2_index(BDRVQEDState *s, uint64_t pos)
259 {
260 return (pos >> s->l2_shift) & s->l2_mask;
261 }
262
263 /**
264 * Test if a cluster offset is valid
265 */
266 static inline bool qed_check_cluster_offset(BDRVQEDState *s, uint64_t offset)
267 {
268 uint64_t header_size = (uint64_t)s->header.header_size *
269 s->header.cluster_size;
270
271 if (offset & (s->header.cluster_size - 1)) {
272 return false;
273 }
274 return offset >= header_size && offset < s->file_size;
275 }
276
277 /**
278 * Test if a table offset is valid
279 */
280 static inline bool qed_check_table_offset(BDRVQEDState *s, uint64_t offset)
281 {
282 uint64_t end_offset = offset + (s->header.table_size - 1) *
283 s->header.cluster_size;
284
285 /* Overflow check */
286 if (end_offset <= offset) {
287 return false;
288 }
289
290 return qed_check_cluster_offset(s, offset) &&
291 qed_check_cluster_offset(s, end_offset);
292 }
293
294 static inline bool qed_offset_is_cluster_aligned(BDRVQEDState *s,
295 uint64_t offset)
296 {
297 if (qed_offset_into_cluster(s, offset)) {
298 return false;
299 }
300 return true;
301 }
302
303 static inline bool qed_offset_is_unalloc_cluster(uint64_t offset)
304 {
305 if (offset == 0) {
306 return true;
307 }
308 return false;
309 }
310
311 static inline bool qed_offset_is_zero_cluster(uint64_t offset)
312 {
313 if (offset == 1) {
314 return true;
315 }
316 return false;
317 }
318
319 #endif /* BLOCK_QED_H */